The overexploitation
of certain fish species has meant that the fishing industry
has directed its attention toward the use of underutilized
species such as mackerel. The effective utilization
of mackerel largely depends on its fat content, and, therefore,
the fishing industry requires analytical techniques to
rapidly grade mackerel according to its composition.
We have developed a hand-held ultrasonic device that can
be used to provide information about fish composition.
The composition is determined from measurements of the
ultrasonic velocity of fish, either at a fixed temperature
or over a range of temperatures. A series of empirical
equations were developed to relate ultrasonic velocity
measurements to fish composition. We demonstrated
that the compositions determined using the ultrasonic
velocity technique were in good agreement with those determined
by official methods for a number of fish species including
cod, mackerel, salmon, and tuna. The technique is
now at the stage where a commercial instrument manufacturer
could develop it, providing there is sufficient interest
and a big enough market in the fishing industry.